Heirs and Heiresses of the Wealthiest People in America

fIn this handout photo provided by Mayor Bloomberg's Press Office, the maid of honor Georgina Bloomberg, left, Mayor Michael Bloomberg and the bride Emma Bloomberg, right, pose for a photo before the ceremony. Emma Bloomberg was married on Saturday in a civil ceremony at the mayor's 26-acre country home in Westchester County.

American parents are some of the most generous givers in the world, planning to leave an average of $175,000 to their children after they retire, according to a new study by HSBC. One out of every five inheritances will be worth more than $390,000.

Coming into that kind of money without having to work for it is nothing to sniff at — but what if you were born into billions?

America is home to the most billionaires in the world — 442 at last count. We decided to take a look at some of the richest American families and turn the spotlight from the billionaires themselves to the heirs and heiresses who are expected to live up to their family fortune.

The Koch Brothers

It’s hard to look at the Koch brothers as simply heirs to their late father’s multibillion-dollar fortune. Charles (left), 78, and David, 74, are worth an estimated $36 billion, making them the richest brothers in the U.S., but they’ve had a hand in the family business for decades. Today, each shares executive roles at Koch Industries, a global conglomerate and the second-largest privately-held company in the U.S., whose subsidiaries are involved in a range of industries, including refining, energy, and building products.

Zachary and Alexa Dell

Their father, Michael Dell, made his fortune founding the largest PC company in the U.S., Dell. Worth $15.9 billion, he’s the 25th richest person in the country.

Alexa Dell, 18, made headlines when she posted a slew of Instagram photos and tweets that revealed her family’s secret vacation spot to the public last year — undoing countless hours of work by their $2.7 million-a-year personal security team to keep their whereabouts private (they were on the family jet on their way to Fiji). Younger brother Zachary is already getting in the entrepreneurial spirit. At age 15, he co-owns a children’s sports camp in Dallas.

Brett Icahn

Brett’s father, Carl Icahn, 77, is the activist investor and founder of Icahn Enterprises and the 18th richest person in the U.S.

Brett, 40, may stand to inherit his father’s fortune, but the hedge fund manager is doing a decent job filling Dad’s shoes already. Carl Icahn threw Brett and his investment management partner, David Schechter, a multibillion-dollar bone in 2012, giving the pair free reign over $3 billion worth of capital from Icahn Enterprises. The move was something of a test, letting the junior Icahn prove his savvy as a hedge fund manager with the hopes of one day launching his own fund. Brett, who joined the family business as an investment analyst more than a decade ago, has produced returns as high as 96% in his new role.

It's good to be a Soros. Their father, George Soros, is a hedge fund manager and philanthropist worth $20 billion.

George Soros’ brood is well on their way to making the most of their father’s massive fortune. The youngest, Gregory, is a self-described artist who listed his Manhattan townhouse for $12 million in April (he purchased it three years ago for $11.9 million). His older brother, Alex, is a philanthropist, sitting on the board of the Open Society Foundation, Jewish Funds for Justice and Global Witness. Older sister Andrea runs her own nonprofit, Trace, which benefits Tibetan education. Andrea made headlines last year when she put her Manhattan townhouse on the market for a cool $30 million. The eldest Soros siblings, Robert and Jonathan, both took to the family business. Robert oversees investments at Soros Fund Management and was later joined by Jonathan, who stepped down in 2012. Jonathan is now a senior fellow at the Roosevelt Institute, a liberal think tank.

The Google Tots

Google co-founders Larry Page (right) and Sergey Brin, both 40, have matching $25 billion fortunes, making them the 12th- and 13th-richest people in the U.S., respectively.

Both are parents to some of the richest toddlers in the world. Page has two children with wife Lucy, born in 2009 and 2011. Brin’s four-year-old son, Benji, was born in 2009 and someone has already purchased the rights to his web domain, Benjibrin.com.

Travis Knight

Travis’s father, Phil Knight, 75, co-founded Nike and is currently the 24th-richest person in America worth an estimated $16.3 billion.

A longtime animator and film executive, Travis, 40, may have distanced himself from his father’s line of work, but it’s clear the family’s flair for entrepreneurship rubbed off. Knight launched LAIKA, Inc., a stop-motion animation film studio, in 2005. His younger brother, Matthew, passed away after suffering a heart attack while scuba diving in El Salvador in 2004. There’s little, if any, public information about their sister, Christina, which may be a sign that Phil’s personal wariness of the media was passed on to his daughter.

The Mars Bars Kids

Jacqueline (pictured; 74), Forrest (82), and John Mars (77)

The heirs to candy mogul Forrest Mars together rank as the 15th-richest people in the U.S., inheriting an estimated $20.5 billion from the family business.

Mars, the world’s largest candy-maker, includes brands like M&Ms, Twix and Uncle Ben’s under its umbrella. The Mars siblings' grandfather, Frank, started the company in 1911 and the trio inherited their stakes after their father passed away in 1999. According to Forbes, Jacqueline is a trustee of the U.S. Equestrian Team; Forrest supports historical preservation initiatives; and John backs the Fred W. Smith National Library for the Study of George Washington in Mount Vernon, N.Y. Between the three of them, they have 13 children.

Megan and David Ellison

The son and daughter of Oracle co-founder and yachting enthusiast Larry Ellison each stand to inherit a piece of Pop’s $41 billion fortune, but they’re not relying on that windfall to sustain them. Since their early 20s, both Megan, 27, and David, 30, have made a name for themselves as film producers in Hollywood. They went on to launch his and her production companies, Skydance Films and Annapurna Productions, which have helped bring blockbusters like “Zero Dark Thirty” and “World War Z” to the big screen. The Wrap called the pair the films industry’s newest “power siblings” in 2010.

The Jeff Bezos Brood

Bezos’s children (one adopted daughter and three biological sons) will stand to inherit their father’s $27 billion fortune.

There’s little if any public information about the four children of Amazon.com founder and CEO Jeff Bezos, 49, has with his wife of 20 years, MacKenzie. The Bezoses are tight-lipped hush-hush about their family, though MacKenzie, also an author, told Vogue magazine that they are between the ages of seven and 12. The pair clearly want to keep them grounded. They eschewed the idea of hiring a nanny to help out, and MacKenzie usually picks up the kids from school in a Honda minivan.

At any rate, the lucky youngsters will stand to inherit at least some of the gains from his growing empire, which includes e-commerce giant Amazon, as well as the Washington Post, and other personal investments.

Abigail Johnson

Abigail Johnson, 51, is worth $17.2 billion thanks to the family business: her grandfather, Edward Johnson II, founded Fidelity Investments in 1945. It is now the second-largest mutual fund firm in the U.S. with $1.7 trillion in assets under management.

Johnson joined Fidelity in the late ‘80s as an analyst and has since worked her way up to President of Financial Services. When her father, Edward, steps down as CEO, she’s expected to take over. Currently, she owns half of her family’s 49% stake in the company, enough to make her the 23rd richest American.

Emma and Georgina Bloomberg

Their father, Michael Bloomberg, 71, has been mayor of New York City for the last 12 years and owes his $31 billion fortune to his 88% stake in Bloomberg, LP, the financial data firm he founded in 1982. He’s the seventh-richest person in the U.S.

Georgina, 30, was once named one of the most intriguing heiresses by Forbes. A professional equestrian, she founded a nonprofit, Rider’s Closet, that donates used equestrian gear to intercollegiate riders. She is expecting her first child this month with her boyfriend, Argentinian equestrian Ramiro Quintana. No stranger to media attention, Georgina offered Glamour a candid look at life with her billionaire father this year and once posed for Hamptons Magazine. Her sister, Emma, is more camera shy but equally accomplished, with the same philanthropic inclinations as her father. She’s currently chief of staff at the Robin Hood Foundation, a non-profit focusing on poverty in New York City.

Christy, Jim, Alice and Robson Walton

The Walton siblings are each worth at least $33 billion thanks to the fortune they inherited from Walmart founder Sam Walton.

Christy Walton (not pictured) became the richest woman in the country when her husband, John Walton, died suddenly in a plane crash in 2005 and she inherited his slice of the family fortune. Along with brother-in-law Jim, Christy earned an estimated $350 million in dividends from her Walmart holdings alone in 2013, according to Forbes. Jim is the CEO of the Walton family's Arvest Bank, which is worth about $1.8 billion. His sister, Alice, has made a name for herself in the art world, founding a successful American art museum, Crystal Bridges, in Arkansas two years ago. Together, the Walton siblings have poured $2 billion into philanthropic efforts through the Walton Family Foundation.